This application is based upon and claims benefit of priority of Japanese Patent Applications No. Hei-11-55215 filed on Mar. 3, 1999, No. Hei-11-209887 filed on Jul. 23, 1999 and No. Hei-11-352244 filed on Dec. 10, 1999, the contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to a device for vaporizing liquid fuel. The vaporized fuel is supplied to various kinds of burners, internal combustion engines or any other like apparatus.
2. Description of Related Art
Liquid fuel vaporizers for supplying vaporized fuel to burners or the like are known and disclosed, for example, in JP-A-6-265111 and JP-A-4-177011. The vaporizer disclosed in those publications includes a combustion chamber in which liquid fuel is burnt, a vaporization chamber in which liquid fuel is heated and vaporized by the heat generated in the combustion chamber. Both chambers are formed separately, and the vaporization chamber is disposed downstream of the combustion chamber. The liquid fuel is supplied to both combustion and vaporization chambers from respective fuel injectors. Because both chambers are made separately and two fuel injectors are necessary in this structure, the device becomes bulky and costly, and is not easy to mount on a device to which the vaporized fuel is supplied.
The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an improved liquid fuel vaporizer in which both combustion and vaporization chambers are housed in a housing and a single fuel injector is used for supplying fuel to both chambers.
A liquid fuel vaporizer according to the present invention is composed of a housing, a combustion chamber, a vaporization chamber and a fuel injector. Both the combustion and vaporization chambers are housed in a housing, and liquid fuel such as gasoline is supplied from a common fuel injector to both chambers. Liquid fuel supplied to the combustion chamber is burnt to generate heat. Liquid fuel supplied to the vaporization chamber is heated and vaporized by the heat generated in the combustion chamber. The vaporized fuel is fed to an outside device such as a burner connected to the liquid fuel vaporizer.
Preferably, both the combustion and vaporization chambers are cylinder-shaped, the combustion chamber being coaxially disposed inside the vaporization chamber, and both chambers are connected to each other by a burnt gas passage. The burnt gas in the combustion chamber is led to the vaporization chamber through the burnt gas passage and heats up the liquid fuel in the vaporization chamber to vaporize the liquid fuel therein. The burnt gas passage serves to introduce the burnt gas into the vaporization chamber and to prevent combustion flame from entering into the vaporization chamber. An injector plate having a set of small holes and another set of large holes is attached to the fuel injector. Fuel injected through the small injection holes is cracked into smaller particles and then supplied to the combustion chamber, thereby improving ignitability of the fuel in the combustion chamber. Fuel injected through the large injection holes is directly supplied to the vaporization chamber.
The liquid fuel may be injected through only one set of injection holes and supplied to both chambers. In this case, a fuel collision block is disposed around the injector, so that part of liquid fuel collides with the block, being cracked into small particles, and then the small particles of fuel are supplied to the combustion chamber to improve ignitability. On the other hand, the liquid fuel is directly supplied to the vaporization chamber without colliding with the block. A fuel absorber may be disposed on the fuel collision block so that liquid fuel adhering to the block upon its collision with the block is temporarily absorbed and vaporized by the heat from the combustion chamber. A series of depressions and projections may be formed in place of the fuel absorber for the same purpose.
An air/fuel ratio in the combustion chamber is controlled within a combustible range, while the air/fuel ratio in the vaporization chamber is controlled in a range that falls out of the combustible range to ensure that no combustion occurs in the vaporization chamber. Alternatively, the burnt gas supplied from the combustion chamber to the vaporization chamber may be cooled down by cooling air to a temperature lower than a level at which fuel in the vaporization chamber is ignited. A mixture of combustible liquid fuel and incombustible fluid may be supplied to both the combustion and vaporization chambers in place of the liquid fuel to prevent combustion of vaporized fuel in the vaporization chamber.
According to the present invention, the whole structure of the liquid fuel vaporizer is simplified because both the combustion and evaporation chambers are integrally housed in a housing and a single injector supplies fuel to both chambers. Moreover, combustion of the vaporized fuel in the vaporization chamber is prevented without fail.
Other objects and features of the present invention will become more readily apparent from a better understanding of the preferred embodiments described below with reference to the following drawings.